Fridge to highland terrarium--sensible?

[schmiggle]

I have been trying to figure out a better way to cool my highland terrarium than simply putting in ice bottles. Today an idea occurred to me that seemed very simple--remove the compressor, the evaporator, and the tubing from an existing fridge, hook it up to a thermostat inside the terrarium, and stick it all right on the outside, essentially turning the terrarium into a refrigerator (but obviously a significantly warmer one). This seems suspiciously simple, but I've never seen it done before, so am I missing something? I should have a free mini-fridge available, so that isn't a problem, and it seemed more energetically efficient than drilling holes in the side of a refrigerator and sticking a whole bunch of tubing with water inside and around the terrarium and pumping it through.